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Determination of Soil Radon-222 Flux at Tree Area With Different Activity Related When use of the Soil in the Eastern Amazon

Risonaldo Leal Lima, Projeto LBA, risonaldo@lbasantarem.com.br (Presenting)
Christopher Martens, North Carolina University, cmartens@mail.unc.edu
Howard Mendlovitz, North Carolina University, mendlovitz@unc.edu
José Mauro Moura, CENA - Centro de Energia Nuclear na Agricultura (USP), jmauro@esalq.usp.br
Irene Cibelle Sampaio, Universidade Federal do Pará, cibelle@lbasantarem.com.br
Carlos Eduardo Guerra, Universidade Federal do Pará, guerra@ufpa.com.br
Rodrigo Silva, Universidade Federal do Pará, rodrigo@lbasantarem.com.br

Radon-222 is a radioactive noble gas, chemically inert with a half life of 3.8 days, emitted mostly from soil, behaving conservatively. As a result, Rn-222 has a strong potential to offer a reliable measurement of biosphere-atmosphere exchange rates of reactive trace gases. Rn-222 soil-air fluxes are a critical component of the Radon budgets used to study these processes. Three sites were included in this study: a Logged Forest (km 83) and Primary Forest (km 67) in the Tapajós National Forest, and an agricultural field (km 77) undergoing periodic crop rotation (rice and soybeans). Ground flux samples were collected three times a week using portable detectors placed on permanent PVC soil collars in areas around the LBA flux towers and record the “soil-air” flux during sequential periods of 60 minutes. These detectors consist of a 15-liter chamber and an electronic part that counts 222Rn. The results showed that the annual variation of the soil Rn-222 flux on period of 2001 did not present a significant statistic different between the site (P>0,05). However, on period of 2002 was noticed a significant statistic different between them (P<0,05). The results suggest that the site of the km 83 and km 67 are similar while the site of the km 77 is different.

Science Theme:  TG (Trace Gases)

Presentation Type:  Poster

Abstract ID: 20

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